Biology Lectures 4-6 Flashcards
(177 cards)
1
Q
What are Lipids?
A
Lipids are LARGE biological molecules which are formed of C, H, O and sometimes P.
2
Q
What are Lipids NOT?
A
Polymers
3
Q
Properties of lipids? Why do they have these properties?
A
Lipids are largely NON-POLAR because mostly made up of C-H and C-C bonds.
Lipids are INSOULBLE in water because the is no slightly positive/ negative end for the water to attract to. Lipids can be SOLUBLE in NON- POLAR solvents.
HYDROPHOBIC interactions cause lipids to group together in water.
4
Q
Give some examples of lipids.
A
FATS- solid at room temperature. OILS- liquids at room temperature. WAXES- solid at room temperature- very hydrophobic. PHOSPHOLIPIDS forms membrane bilayer. STEROIDS
5
Q
What are Triglycerides?
A
Type of dietary fat.
6
Q
What are Triglycerides formed of?
A
Formed of 1 GYCEROL (backbone) and 3 FATTY ACID chains.
7
Q
What bond is present between a fatty acid chain and glycerol?
A
ESTER BOND.
8
Q
How are Triglycerides formed?
A
DEHYDRATION synthesis (condensation reactions).
9
Q
How are Triglycerides broken down? What enzyme does this require?
A
HYDROYLSIS reactions which requires the intestinal enzyme TRIGLYCERIDE LIPASE.
10
Q
Why are Triglycerides broken down?
A
Free fatty acids are more easily absorbed in the gut and transported.
11
Q
Name the two types of classes of Triglycerides.
A
Saturated and Unsaturated.
12
Q
What are Saturated fatty acids? Give an example of a saturated fatty acid.
A
SATURATED fatty acids contain SINGLE carbon- carbon bonds. Examples include PALMITATE.
13
Q
What type of triglyceride does saturated fatty acids form. Give an example of one.
A
SFAs (Saturated Fatty Acids) form COMPACT, closely packed triglycerides that are solid at room temperature, for example Palmitic acid present in plant and animal fats.
14
Q
What are unsaturated fatty acids. Give an example of a unsaturated fatty acid.
A
UNSATURATED fatty acids contain 1 or more carbon- carbon DOUBLE bonds. Examples include OLEATE.
15
Q
What type of triglyceride does unsaturated fatty acids form. Why? Give an example of one.
A
UTAs (Unsaturated Fatty Acids) form LOOSELY packed triglycerides due to the double bonds and is a liquid at room temperature, for example Olive Oil.
16
Q
What are free fatty acids?
A
Are when the fatty acid is not part of a triglyceride.
17
Q
Why are free fatty acids essential?
A
NOT synthesised by the body.
18
Q
How do you name an “omega FFAs”?
A
find the location of the first double bond counting from the methyl end.
19
Q
What is the basic structure of steroids?
A
FOUR FUSED CARBON RINGS with various side groups.
20
Q
What is the building block of steroids?
How is the building block formed?
A
LANOSTEROL is the building block of all steroids and is formed by the cyclization of SQUALENE (long chain).
21
Q
Name some examples of Steroids.
A
Cholesterol, sex hormones like Oestrogen, Corticosteroids produced in the adrenal cortex and with many functions include controlling inflammation as well as Vitamin D.
22
Q
What are phospholipids?
A
PHOSPHOLIPIDS are lipids with a PHOSPHATE GROUP COVALENTLY bonded to the glycerol backbone instead of a fatty acid.
23
Q
Properties of a phosphate group and a fatty acid group.
A
PHOSPHATE GROUP Polar Soluble in water (hydrophilic) head FATTY ACID GROUPS Non-polar Insoluble in water (hydrophobic) Tail
24
Q
What ways can phospholipids be arranged in water? Why?
A
MICELLE which is a spherical arrangement of lipid molecules or a BILAYER which is composed of two layers of lipids organised as a sheet.
Phospholipids like to keep their “HEADS WET” and their “TAILS DRY.”
25
What are glycolipids?
GLYCOLIPIDS are lipids which are COVALENTLY attached to an OLIGOSACCHARIDE (3-20 monomers).
26
What do glycolipids form part of?
Form part of the cell membrane and glycocalyx, carbohydrate enriched coating that covers the outside of eukaryotic and prokaryotic cells in particular bacteria.
27
What are lipoproteins? Where are they found?
LIPOPROTEINS are soluble complexes that transport lipids and are synthesized in the liver.
28
What Spherical particles have a central HYDROPHOBIC core?
Triglycerides
Esterified cholesterol (cholesteryl ester)
Small amounts of other lipids and fat soluble vitamins.
29
What particles have an External HYDROPHILIC layer:
```
Phospholipids
Cholesterol (OH functional group)
Apoproteins- Stabilise structure and regulate enzymatic activity at the lipoprotein interface.
```
30
Lipoprotein- What fat does Chylomicrons carry? From where to where?
Carry dietary fat from small intestine to liver.
31
What does VLDL stand for?
Where are VLDL produced and what are they synthesised from?
What fat does it carry?
How does VLDL become IDL and then LDL?
Very Low Density Lipoprotein.
Produced in Liver and synthesised from Triglycerides and Cholesterol Ester.
Gradually TGs are removed to produced Intermediate Density and Low Density Lipoproteins.
32
What does HDL stand for?
What does HDL do? Why?
What is the condition?
High Density Lipoprotein
HDL carries (good) cholesterol to the liver which reduces atherosclerosis.
Atherosclerosis is a serious condition where arteries become clogged with fatty material. Sites of fatty deposition called plaques.
33
What is the optimal lipoprotein profile?
HDL: >60 mg/dL
LDL: 60- 130 mg/dL
TGs: <150 mg/dL
Total Cholesterol: < 200 mg/dL
34
How triglycerides stored? Where are they stored?
Lipid droplets in the cytoplasm of ADIPOCYTE cells in ADIPOSE TISSUE.
35
What does white adipose tissue do?
```
Cushion internal organs
Acts as a shock absorber
Gives insulation
Reduces Skin Heat loss
Protects internal organs from temperature change.
```
36
Name an example of where white adipose tissue is found.
Gluteals
37
What is the main function of brown adipose tissue? What does it have which allows to carry out this function.
BROWN adipose tissue is useful for generating body heat as in the adipocytes cells there are lots of fat vacuoles and mitochondria.
38
Name a location in the body where brown adipose tissue is found.
Neck
39
What can excess adipose tissue lead to?
Atherosclerosis
Thrombosis- clotting of circulating blood
Stenosis- abnormal narrowing of blood vessel
Aneurysms- blood- filled bulges in a blood Bessel wall.
Exerts undue pressure on organs and is a major endocrine organ which produces pro-inflammatory hormones such as leptin and the cytokine TNFα.
40
What insulation do phospholipids provide? What does this insulation do?
MYELIN INSULATION around nerve fibres.
| Myelin increases the speed of nerve impulses.
41
What are the functions of Vitamins A, D, E and K which are fat soluble and some are lipid/ steroid derived.
Vitamin A- Retinol- Health teeth, skin and sight.
Vitamin D- Cholecalciferol- Helps body absorb Ca2+ for health bones.
Vitamin E- Tocopherol found in oils- Anti- Oxidant, protects cells from damage.
Vitamin K- Phylloquinone and Menaquinone- Important for coagulation of blood.
42
Chemical messengers and are steroidal hormones are derived from what?
Cholesterol
43
Lipid layers can prevent what, especially in the eye and on the skin?
EVAPOURATION of water.
A Lipid layer on tear film reduces moisture loss from the CORNEA.
44
What are proteins?
Proteins are POLYMERIC, chain- like molecules which have fundamental cellular components which are vital for all cellular functions.
45
What is a polypeptide?
A POLYPEPTIDE is amino acid monomers linked together by PEPTIDE BONDS
46
How many amino acids is a polypeptide made up of?
More than 40 amino acids and can fold to determine shape.
47
What does the protein sequence determine?
SHAPE and FUNCTION of a protein.
48
How many amino acids are there?
20 amino acids.
49
What do all amino acids have? Is there any exceptions?
All amino acids have a CHIRAL CARBON, a CARBOXYL GROUP, an AMINE GROUP. Each Amino acid has a different side chain (R group). Apart from one exception, the Carbon in all amino acids is chiral.
50
What is a chiral carbon?
A CHIRAL CARBON is an atom in a molecule which is bonded to 4 different chemical species.
51
Since all amino acids have a chiral carbon they have two what? What are there names? Which occurs more in nature?
Two ENANTOMERS which are NOT SUPERIMPOSABLE MIRROR IMAGES or L and D forms. L form is dominate with the D form rare in nature.
52
Amino Acid Ionisation- in a low pH environment what happens to concentration of H+ so what amino acid is favourable there?
In a LOW pH environment there is a HIGH concentration of H+ ions so the amino acid gains a H+ ion on the amine group and so has a POSITIVE charge on the amine group.
53
Amino Acid Ionisation- in a high pH environment what happens to concentration of H+ so what amino acid is favourable there?
In a HIGH pH environment there is a LOW concentration of H+ ions so the amino acid loses a H+ ion from the Carboxyl group and so has a NEGATIVE charge on the carboxyl group.
54
What is a Zwitterion seen as?
The middle- Has an extra H+ on NH2 and COO-
55
What determines the properties of an amino acid?
R group.
56
Classify the amino acids into different R groups.
Hydrophobic:
9 Non polar
Hydrophilic:
6 Polar
2 Acidic
3 Basic
57
What amino acids have non- polar R groups?
```
Glycine (gly)
Alanine (Ala)
Valine (Val)
Leucine (Leu)
Isoleucine (ile)
Methionine (Met)
Phenylalanine (Phe)
Tryptophan (Trp)
Proline (Pro)
```
58
Name the amino acids which have acidic R groups? Why do they have acidic R groups?
What is an acid?
Aspartic Acid and Glutamic Acid
In NORMAL conditions Asp and Glu have a lower pKa so are a stronger acid so will LOSE protons off the OH and become O- so are negatively charged.
ACID= PROTON DONER
59
Name the amino acids which have basic R groups? Why do they have basic R groups?
What is an base?
Lysine (lys)
Arginine (Arg)
Histidine (his)
In NORMAL conditions Lys, Arg and His have a higher pKa so are a weaker acid so will GAIN protons and become NH3 + so is positively charged.
BASE= PROTON ACCEPTOR
60
Name the amino acids which have polar R groups? What is these groups main property?
```
Tyrosine (Try)
Asparagine (Asn)
Glutamine (Gln)
Serine (Ser)
Threonine (The)
Cysteine (Cys)
```
Can form hydrogen bond interactions with similar side-chains and peptide bonds.
61
What can the Amino Acid Cys form?
can form disulphide bridges which is a COVALENT link between two Sulphurs on two different polypeptides.
62
How are polypeptides formed?
What is the name of the reaction?
What bond is formed in this reaction?
Polypeptides are formed by DEHYDRATION SYNTHESIS which is achieved via linkage of -COOH and -NH2.
A WATER molecule is removed in a CONDENSATION REACTION which results in the formation of a PEPTIDE BOND.
63
Describe a peptide bond. Why does the bond have these properties?
Peptide bonds are RIGID and PLANAR because of the electrons in the bond.
Rotation at C is usually limited by steric clashes between bulky R groups, so the TRANS form is the most common.
64
What is the primary structure of a protein?
Amino acid sequence.
65
What is the secondary structure of a protein?
Interactions between adjacent amino acids. Examples include α helices, b- sheets, loops/random coils.
66
What is the tertiary structure of a protein?
3D folding of a single polypeptide chain.
67
What is the quaternary structure of a protein?
Assembly of multiple proteins into a complex.
68
What determines the amino acid sequence?
DNA sequence of GENES for each protein
69
What will alter the primary sequence of a protein? Give an example.
Genetic mutations which alter the primary structure cause a change to the STRUCTURE and FUNCTION of the protein, for example sickle cell disease.
70
What do Alpha helices and beta pleated sheets do in the secondary structure?
ALPHA HELICES and BETA PLEATED SHEET are parts of the polypeptide chains that take on regular patterns of hydrogen bonding. The patterns are connected by SHORT TUNRS and longer LOOPS/ RANDOM COILS.
71
What is the structure of an alpha helix?
coiled rod- like structure
72
What disrupts a- helices?
PROLINE
73
Where are alpha helices found and absent?
A-Helices are abundant in HAEMOGLOBIN and absent in CHYMOTRPSIN which is a digestive enzyme.
74
How are alpha helices stabilised?
Extensive INTRA-CHAIN hydrogen bonding
75
How many amino acids are there per turn? Which way does the turn go?
3.6 amino acids per turn with the turns CLOCKWISE from N to C- terminal end.
76
What bond forms the backbone?
| Where do the R groups go in the structure?
Peptide bonds form the backbone with R groups project OUTWARDS to avoid steric hindrance.
77
What are Beta- Sheets?
Beta pleated sheets are flat sheet which are short runs of 5-10 amino acids. They can run either PARALLEL, ANTI-PARALLEL or MIXED.
78
What are some of a Beta- Sheets properties?
B- pleated sheets are STRONG and RESILIENT and multiple sheets are connected by short turns or HAIRPIN LOOPS.
79
How are beta sheets held together?
They are held together by HYDROGEN BONDS between peptide bonds on adjacent strands.
80
Out of a-helices and b-sheets which one has longer distance between amino acids. So?
LONGER distance between amino acids in a Beta sheet so they are more flexible than alpha helices.
81
What is the range of a length of a B-sheet?
Length of a B-sheet can range from 2-22 amino acids.
82
What do loops and random coils do?
| How do they do this? How many amino acids are present in the loops/ random coils?
Loops and Random coils CONNECT secondary structural elements TOGETHER and are usually located on the surface. They are rich in POLAR and CHARGED amino acids with length varying between 2-20 amino acids.
83
If two proteins are structurally similar, where would the difference be?
Typically occurs in the loops.
84
What is the function of a structural motif?
Associated with biological function of protein- joins A-helices and B-Sheets together..
85
What is a B- Hairpin Motif?
Where are they common?
Function?
Two adjacent ANTI-PARALLEL B-strands joined by a HAIRPIN LOOP. They are the SIMPLEST super secondary structure. They are common in globular proteins and there is no specific function associated with this motif.
86
What is a Helix- Loop- Helix Motif?
Functions?
Where are they common?
TWO ALPHA HELICES connected by a LOOP. Functions as either DNA BINDING or CA2+ BINDING.
Common in TRANSCRIPTION FACTORS and CELL SIGNALLING PROTEINS that bind to Ca2+.
87
What is a Greek Key motif?
Functions?
Where are they common?
THREE ANTI-PARALLEL B-strands connected HAIRPIN LOOPS with the 4th strand adjacent to the 1st strand and linked to the 3rd by a larger loop.
Common in a range of proteins but NO SPECIFIC FUNCTION.
88
What is a Coiled coil motif?
| Example?
Motif usually contains repeat of 7 RESIDUE (Amino acid) pattern (hxxhcxc) with h being hydrophobic, c being charged and then x being any amino acid.
This pattern results in AMPHIPATHIC (amino acids hydrophobic and hydrophilic) a-helices which have a ‘stripe’ of hydrophobic residues that coil around similar strips in other helices and then hydrophilic residues project outwards. Two helices are joined together by the hydrophobic residues coiling together.
Examples in structural proteins, MYOSIN.
89
What is a Zinc Finger Motif?
Where are they common?
Functions?
TWO ANTI- PARALLEL b-sheets followed by 1 a-helix which is STABILISED by a zinc ion. Strands may bind to iron or no mental at all.
Metal binding is medicated by CYS in B-Sheets and HIS in a-helix.
Zinc finger motif is common in many proteins including TRANSCRIPTION FACTORS.
Many can be present in the same polypeptide chain.
The functions of the Zinc finger motif include BINDING DNA and RNA, LIPID and PROTEIN SUBSTRATES.
90
What is a beta barrel Motif?
| Name some examples of this motif.
Beta barrel motif is MUTIPLE ANTI- PARALLEL B-sheets that twist to form a closed structure. The first strand is HYDROGEN bonded to the last.
Types of this motif include Greek key barrel, up-and-down barrel, jelly roll barrel and beta- helix barrel.
Also there is a pore-forming water channels called aquaporins.
91
What is a domain?
What does a domain form from?
How many domains can a protein have?
What is each domain associated with?
A domain helps the protein carry out its FUNCTION. It is a POLYPEPTIDE CHAIN that folds INDEPENDENTLY into a stable structure with its own HYDROPHOBIC CORE.
The domain forms from several simple motifs and secondary structure elements. A protein can have one domain or lots. Each domain is associated with a DISTINCT biological function.
92
What is tertiary structure held together by? List how each structure tool does this.
HYDROGEN BONDS between the R groups
IONIC BONDS, which is electrostatic attraction between oppositely charged ions, between CO2- and NH3+ of R groups.
DISULPHIDE BRIDGES, which are covalent crosslinks, between cysteine -SH groups.
HYDROPHOBIC INTERACTIONS between hydrophobic R groups clusters inside proteins to shield themselves from water.
93
What are the 2 roles of fibrous proteins?
Fibrous proteins have important roles providing SUPPORT and STRENGTH.
94
What do secondary structures go on to form?
SECONDARY structures from long PARALLEL fibres and sheets which are usually insoluble in water.
95
What is collagen made up of?
Collagen is made up of super- helices of GLY rich a- helices (TROPOCOLLAGEN) that assemble into fibrils.
96
What does collagen mainly make up?
CONNECTIVE TISSUE which supports, connects and separates tissues and organs. Collagen makes up 25% of the connective tissue and it is strong and elastic.
97
Where can collagen be found?
BONES, TENDONS, SKIN, CARTILAGE, TEETH, LIGAMENTS, BLOOD VESSELS and EYES.
98
What is EDS?
| How is it caused and what does it effect?
EDS is a genetic connective tissue disorder where structure, production and processing of collagen is affected. It is caused by multiple mutations in multiple genes and can affect the skin, musculoskeletal and cardiovascular systems.
99
What does A- Keratins make up?
| What is it composed of?
A- KERATINS make up HAIR and NAILS in mammals. It is composed of COILED- COILS of TWO a- helices that assemble together into larger fibres.
100
List the properties of A- Keratins.
| What is between the coiled- coils in A- Keratins?
A-Keratins are strong, insoluble and chemically inert. There are DISULPHIDE BRIDGES cross links between the coiled- coils.
101
What do B- Keratins make up?
B- KERATINS make up REPTILE SCALES, CLAWS and BEAKS in birds.
102
What is Fibroin? What is it made up of?
| In fibroin what do the small side chains allow for?
FIBROIN is a type of B- keratin which is found in spider webs. Fibroin is made of anti- parallel B-sheets which are rich in ALA and GLY residues. In Fibroin there are small side chains to allow close packing of b- sheets. Sheets joined by amorphous (lacks definite shape) stretches for ELASTICITY and STRENGTH.
103
What are globular proteins?
| Why are globular proteins usually soluble in water?
Globular proteins are a MIXTURE of IRREGULARLY folder secondary elements to form a compact 3-D shape. Globular proteins are usually soluble in water with inner hydrophobic core and is easily transported in body fluids.
104
Globular proteins are common structure of ______________
ENZYMES
105
Haemoglobin is a ____________
| What is this?
TETRAMER
| OLIGOMER formed of 4 MONOMERS
106
What is Haemoglobin made up of?
| What does haemoglobin do?
Haemoglobin is made up of 4 POLYPEPTIDE chains and 4 HAEM molecules as well as MYOGLOBIN which exists as a single polypeptide.
Haemoglobin TRANSPORTS O2 from lungs to the rest of the body and RELEASES O2 to permit aerobic respiration to provide energy.
107
What causes Sickle Cell Disease?
Sickle cell disease is a disease which is caused by a single gene defect as a SINGLE mutation in the DNA coding region within the B- globin gene.
108
What type of mutation occurs in Sickle Cell Disease?
This mutation is a MISSENSE mutation which causes a change to the primary structure. The Glu amino acid is changed to the Val amino acid.
109
In Sickle Cell Disease what does the mutation cause?
Mutation causes shape change to the red blood cell so it becomes sickle shaped. The shape change to the cell causes the red blood cells to become rigid and can cause blockages in the capillaries and so individuals can experience organ damage and pain.
110
What are the results of having sickle cell disease?
Furthermore, individuals with the disease can experience increased haemolysis, red blood cell destruction and can cause Anaemia.
111
Why is it beneficial to be a carrier of sickle cell disease?
Protection against MALARIA
112
What are immunoglobulins?
Immunoglobulins are Y-shaped proteins of the immune systems which IDENTIFY and COMBAT invading foreign organisms.
113
What are immunoglobulins made up of?
Immunoglobulins are 4 CHAINS linked by DISULPHIDE BRIDGES. There are 2 large H (heavy) chains and 2 short L (light) chains.
Variable structures in H and L chains form specific binding sites for ANTIGENS.
114
What is denaturation?
DENARTURATION is the process in which proteins lose quaternary, tertiary and secondary structure present in their native state due to a change in environment.
115
Why can pH cause denaturation in proteins?
Ionic bonds are very sensitive to pH. Can in pH can BREAK the ionic bonds which DISRUPTS the tertiary structure and can render proteins insoluble in water and precipitate out of solution.
116
Having a low pH causes what to happen to the amino acid?
LOW pH is a HIGH H+ concentration so ADDING H+ neutralises the COO- part of the ionic bond and so removes its charge.
117
Having a high pH causes what to happen to the amino acid?
HIGH pH is a LOW H+ concentration so by REMOVING H+ neutralises the NH3+ part of the ionic bond and so removing its charge.
118
If you wanted to denature a protein, how would you know what pH to use?
The pH required to denature a protein will vary depending on the properties of that protein.
119
Why can heat cause denaturation in proteins?
Increase in temperature causes more VIBRATIONS which BREAKS the hydrogen and ionic bonds. Denaturation can render proteins insoluble in water and can precipitate out of solution.
120
What is pyrexia?
PYREXIA is an increase in body temperature to fight a fever and is an ancient anti- viral defence mechanism.
121
What are thermos aquatics? What is this used in?
Thermus aquaticus is a bacteria which can survive living in extreme heat. It produces DNA polymerase that is stable at very high temperatures and is essential for Polymerase chain reaction (PCR).
122
Why can solvents cause denaturation in proteins?
Organic solvents, such as Ethanol, forms NEW hydrogen bonds with protein side chains and backbone. These solvents DISRUPTS the intra- and inter-chain hydrogen bonds and causes the protein to unfold and denature.
123
What are the 2 components of the cytoplasm? Give there definitions.
Cytosol- intracellular FLUID
| Organelle- SPECIALISED structure which co-operate to main HOMEOSTATIS.
124
What is the total volume of cytosol in a cell?
How much water is in the cytosol?
What does the cytosol contain?
What occurs in the cytosol?
55%
75-90%
It contains dissolved ions, glucose, amino acids, ATP, lipids and waste products. Wide range of ENZYMATICALLY- controlled REACTIONS.
125
What does the cytoskeleton consist of?
Network of PROTEIN FILAMENTS
126
What are the functions of the cytoskeleton?
1. Helps cells maintain their SHAPE and INTERNAL ORGANISATION.
2. Provides MECHANICAL SUPPORT that enables cells to carry out essential functions like division and movement.
127
What are the three components of the cytoskeleton?
1. Microfilaments
2. Intermediate filaments
3. Microtubules
128
Where are the microfilaments in the cell?
| What proteins make up Microfilaments?
Microfilaments surround EDGE of the cell. ACTIN and MYOSIN are proteins which MAKE UP the MICROFILAMENTS.
129
What are the functions of microfilaments?
1. Microfilaments help generate MOVEMENT in contraction, locomotion and cell division.
2. Provide MECHANICAL SUPPORT needed for cell STRENGTH and SHAPE.
3. Create MICROVILLI in the small intestine.
130
Where are the intermediate filaments found in the cell?
| What proteins make up the intermediate filaments?
Intermediate filaments are very strong and are found in parts of the cell subject to mechanical stress. Proteins which make up intermediate filaments include KERATIN, VIMENTIN and LAMIN.
131
What are the functions of the intermediate filaments?
1. Help STABLISE the POSITIONS of ORGANELLES.
132
What are microtubules?
What are microtubules made from?
Where are microtubules found in the cell?
Where are the formed?
Microtubules are long, unbranched hollow TUBULES (tiny tubes) made from the protein TUBULIN. Microtubules are made up of Alpha- Tubulin and Beta- Tubulin.
They form in the CENTROSOME and then radiate outwards.
133
What are the functions of the microtubules?
1. Helps with CELL STRENGTH, SHAPE and MOVEMENT of organelles such as vesicles and during division.
2. Helps provide STRUCTURE to flagella.
134
Comparison between Different Components of the Cytoskeleton.
MICROTUBULES:
Thickest
Cell Structure and Cell mobility.
Tubulin
MICROFILAMENTS:
Thinnest
Internal Movement within cell
Actin and Myosin
INTERMEDIATE FILAMENTS:
Intermediate
More permanent fixtures
Keratin.
135
What is the centromere made up of?
2 centrioles which are perpendicular to each other.
Each centriole is composed of a circle of 9 clusters of 3 microtubules in each. PERICENTRIOLAR material surrounds the centrioles and consists of numerous RINGS of tubulin.
136
What are the functions of the centromere?
1. Main MICROTUBULE ORGANISAING CENTRE.
2. Regulator of CELL CYCLE PROGRESSION.
3. Growth of MITOTIC SPINDLE during cell division.
137
What is PERICENTRIOLAR material?
Material made up from the same material as the centriole, outside the centrioles.
138
What is the difference (centromere) between a dividing Eukaryotic cell and a cell which is not dividing?
Most microtubules SPREAD OUT from the centrosomes. When a cell is not dividing there is a SINGLE centrosome present. However, when a cell begins to divide the centrosome is REPLICATED EARLY In the process. The SPINDLE APPARTUS in the centrosome begins to form.
139
What is cilia primarily made from?
| Describe the structure of cilia.
Microtubules.
Made up of numerous short hair like projections on the cell surface which are motile (mobile). Each cilium is anchored to a BASAL BODY. CORE of microtubules, 9 PAIRS of microtubules which encircle a CENTRAL PAIR, which are all ENCLOSED in a membrane.
140
What is the function of Cilla?
1. TRANSPORT of FLUID along cells surface.
141
What destroys the Cilla? What does this result in?
Smoking destroys cilia which can result in build-up of dust mucus and bacteria in the lungs causing persistent coughing.
142
What is the difference between flagella and Cilla?
Flagella have a similar structure to cilia but are much LONGER and often only ONE is found on the cell. For example, a sperm tail.
143
What is the function of flagella?
1. Allow cell to SWIM/MOVE.
144
Comparison between Cilia, Flagella and Microvilli.
Cilia:
Found: Ciliated epithelia cells in the lungs.
Function: Wave rhythmically to move dirt and mucus out.
Flagella:
Found: Some bacteria and sperm cell.
Function: Allow cell to swim/move.
Microvilli:
Found: Small Intestine
Function: Increase the surface area for nutrient absorption.
145
What is the endoplasmic reticulum?
The ENDOPLASMIC RETICULUM is a network of MEMBRANES in the form of FLATTERNED SACS and TUBULES extending from nuclear envelope.
146
What is the difference between the rough/ smooth endoplasmic reticulum?
Ribosomes- RER site of protein synthesis.
147
What is the function of the Rough ER?
1. Proteins made by the ribosomes enter the endoplasmic reticulum space for PROCESSING and SORTING.
2. Enzymes (proteins) attach CARBOHYDRATE groups or attach the proteins to PHOSPHOLIPIDS.
148
Why are the functions of the SER greater than the RER?
SER has a greater range of enzymes.
149
What are the functions of the SER?
1. Synthesizes FATTY ACIDS and STEROIDS such as estrogens.
2. In the liver, it helps RELEASE GLUCOSE from gluc-6-p and DETOXIFY lipid soluble drugs like alcohol.
3. STORES Ca2+ ions in the muscles.
150
What does a ribosome consist of? Where are they synthesized?
Large and Small Subunits which with are synthesized separately in the nucleolus.
151
How many proteins does a ribosome each contain?
50 proteins.
152
Where are ribosome located in the cell?
Free in the cytoplasm
Mitchondria
Attached to the Endoplasmic Reticulum.
153
What is the function of a ribosome?
1. Site of PROTEIN SYNETHSIS.
154
What does the golgi complex consist of?
| How are they arranged?
3-20 membranous cristernae (sac like structures).
| Arranged in a sack.
155
How do polypeptides get to the golgi complex?
Transport vesicles containing polypeptides bud off from the Rough endoplasmic reticulum and fuse with the CIS face of the Golgi apparatus releasing the polypeptide into the lumen of the Golgi apparatus. The polypeptide exits at the TRANS face which faces the plasma membrane.
156
What are the sacs called in the golgi complex between the cis and trans faces?
Medical Cisternae.
157
What are the functions of the golgi complex?
1. MODIFYING, SORTING and PACKAGING PROTEINS.
2. TRANSPORT of LIPIDS around the cell.
3. CREATION of LYSOSOMES.
158
What is the function of the lysosome?
1. DIGESTION of substances ENTERING the cell, worn out ORGANELLES (AUTOPHAGY) and ENTIRE CELLS (AUTOLYSIS).
159
What is autolysis?
Autolysis is the digestion of entire cells, whereas autophagy is the digestion of worn out organelles.
160
What is apotosis?
APOTOSIS is “PROGRAMMED CELL DEATH” to remove tissues for example menstruation.
161
What is autophagy?
Autophagy is required for RENEWAL, CELLULAR DIFFERENTIATION and control of GROWTH and TISSUE remodelling.
162
What causes tay Sachs disease?
What happens if the enzyme is absent?
What are the consequences for a patient that has tay Sachs disease?
Mutation in the lysosomal enzyme Hex A- breaks down glycolipids.
glycolipids build up and destroy nerve cell function. The patient can suffer seizures, muscle rigidity and become blind. Often death occurs before age 5.
163
What cell organelle are peroxisomes similar too? Why are peroxisomes different?
Lysosomes but are smaller and contain oxidases.
164
What do peroxisomes do? How do they carry out there function?
What other enzyme do peroxisomes contain? Why?
Peroxisomes are involved with amino acid and fatty acid metabolism (break down). Peroxisomes OXIDISE toxic substances such as alcohol. Also Peroxisomes contain enzyme CATALASE to protect against toxic effects of HYDROGEN PEROXIDE which is made in oxidation reactions.
165
Where in the body is a large number of peroxisomes found?
Liver.
166
Name some examples of peroxisomal disorders.
```
Zellweger Syndrome (ZS)
Neonatal adrenoleukodystrophy (NALD)
Rhizomelic chondrodysplasia punctate.
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167
What is the difference between lysosomes and proteasome? Why do proteasome do that?
Lysosomes degrade (breakdown) proteins delivered in vesicles. Proteasomes degrade (breakdown) ‘free’ CYROSOLIC PROTEINS (proteins in the cytoplasm) which are UNNEEDED, DAMAGED or FAULTY.
168
What cell organelle has only recently been discovered?
Protease Enzyme.
169
What enzyme does Proteasome contain?
PROTEASE ENZYME.
170
What are the mitochondria nicknamed?
POWERHOUSE OF THE CELL.
171
How many mitochondria do cells have?
100-1000 depending on function.
172
What are the functions of the mitochondria?
1. Site of AREOBIC RESPIRATION- Glucose is converted into energy in the form ATP.
2. CELL SIGNALLING
3. CELL GROWTH
4. CELL DEATH
5. CELL DIVISION
173
What processes occur in the mitochondria to produce ATP?
KREBS CYCLE and ELECTRON TRANSPORT CHAIN
174
How is the structure of the mitochondria related to its function?
Intermembrane Space- Small space which quickly accumulates protons.
Inner membrane- Contains ATP synthase and ECT for oxidative phosphorylation.
Cristae- Highly folded so increase in Surface Area: Volume Ratio.
Outer membrane- Transport proteins for shuttling pyruvate into mitochondrion.
Matrix- Appropriate enzymes and a suitable pH for Krebs Cycle.
175
In the nucleus what do nuclear pores allow to occur?
Channels for ions and active transport for RNAs and proteins.
176
In the centre of the nucleus what is present? What are they?
In the centre of the nucleus, a spherical bodies called the NUCLEOLI is present. They are clusters of proteins, DNA and RNA, which are responsible for producing ribosomes.
177
What is transcription and in what organelle does it occur in?
The process of constructing a messenger RNA molecule using a DNA strand as a template which results in the transfer of genetic information to messenger RNA.
Nucleus.
